Distributions and hydrogen isotopic compositions of plant leaf wax from Orinus kokonorica along a general aridity gradient around Lake Qinghai,China

To quantitatively analyze the response of distributions and hydrogen isotopic compositions （SD） of plant leaf wax to moisture, and to better understand their implications for paleoclimatic reconstruction, we measured av- erage chain length （ACL） and 8D values of n-alkanes and n-fatty acids （n-FAs） from Orinus kokonorica, a typical and representative plant in Lake Qinghai area, along a distance transect extending from lakeshore to wetland to dry- land in the arid ecosystem. The results showed that the ACL values of n-alkanes and n-FAs were negatively corre- lated with soil water content （SWC） with R2~0.593 and R2=0.924, respectively. This is as a result of plant＇s response to water loss with more abundance in long-chain n-alkyl lipids under increasing aridity by analyzing relationships between the molecular ratios of long-chain n-alkyl lipids （n-alkanes and n-FAs） from O. kokonorica and SWC. The 8D values of C29 n-alkane and C28 n-FA were also negatively correlated with SWC with R2-0.778 and R2-0.760, respectively, which may due to enhanced D-enrichment in leaf water by evapotranspiration （soil water evaporation and leaf water transpiration） with increasing aridity. Our results demonstrated that moisture exerts a significant con- trol on the ACL and 8D values from O. kokonorica in an arid ecosystem. This preliminary study on a modern single plant （O. kokonorica） sets a foundation for comprehending these values as quantitative proxies for paleo-humidity reconstruction.     

计算岩石波速空间平均的极限近似模型

本文在传统的岩石波速空间平均模型（Voight模型,Ruess模型,Hill模型和几何平均模型）的基础上,提出了一种极限近似模型.在这种模型中,它是利用作者提出的一个基于Hill模型（即代数平均模型）和几何平均模型的递推关系式,并利用这个关系式计算求出模型的极限近似值,该值介于Hill模型和几何平均模型之间,是具有典型代表意义的一个值.     

Sea ice thickness measurement in spring season in Bothnian Bay using an electromagnetic induction instrument

As an important component of the cryosphere,sea ice is very sensitive to the climate change.The study of the sea ice physics needs accurate sea ice thickness.This paper presents an electromagnetic-induction(EM) technique which can be used to measure the sea ice thickness distribution efficiently,and the successful application in Bothnian Bay.Based on the electromagnetic field theory and the electrical properties of sea ice and seawater,EM technique can detect the distance between the instrument and the ice/water interface accurately,than the sea ice thickness is obtained.Contrastive analysis of the apparent conductivity data obtained by EM and the value of drill-hole at same positions allows a construction of a transformable formula of the apparent conductivity to sea ice thickness.The verification of the sea ice thickness calculated by this formula indicates that EM technique is able to get reliable sea ice thickness with average relative error of only 12%.The statistic of all ice thickness profiles shows that the level ice distribution in Bothnian Bay was 0.4-0.6 m.     

基于融合算法的无人机影像拼接缝消除研究

无人机影像在获取和拼接过程中,会有多种因素造成拼接缝。本文对影像拼接缝的特征进行了研究,并利用对应像素直接平均法和加权平均法对实验选取的拼接缝进行了处理比较,结果显示,基于直接平均法融合结果的两条拼接线虽然有所弱化,但肉眼仍然可见;使用加权平均法融合结果较好,但二者均存在重叠区域模糊的现象。     

Three-dimensional discrete element method parallel computation of Cauchy stress distribution over granular materials

The paper presents Cauchy stress tensor computation over parallel grids of message passing interface (MPI) parallel three-dimensional (3D) discrete element method (DEM) simulations of granular materials, considering spherical and nonspherical particles. The stress tensor computation is studied for quasi-static and dynamic conditions, and its resulting symmetry or asymmetry is discussed within the context of classical continuum mechanics (CCM), granular materials mechanics (GMM), and micropolar continuum mechanics (MCM). The average Cauchy stress tensor computation follows Bagi's and Nicot's formulations and is verified within MPI parallel 3D DEM simulations involving dynamically adaptive compute grids. These grids allow calculation of temporal and spatial distributions of stress across granular materials under static and dynamic conditions. The vertical stress component in gravitationally deposited particle assemblies exhibits nonuniform spatial distributions under static equilibrium, and its zone of maximum value changes during the process of gravitational pluviation and collapse. These phenomena reveal a microstructural effect on stress distribution within granular materials that is attributed to their discrete particulate nature (particle size, shape, gradation, boundary conditions, etc).     

A stochastic framework for downscaling processes of spatial averages based on the property of spectral multiscaling and its statistical diagnosis on spatio-temporal rainfall fields

Spectral multi-scaling postulates a power-law type of scaling of spectral distribution functions of stationary processes of spatial averages, over nested and geometrically similar sub-regions of the spatial parameter space of a given spatio-temporal random field. Presently a new framework is formulated for down-scaling processes of spatial averages, following naturally from the postulate of spectral multi-scaling, and key ingredients required for its implementation are described. Moreover, results from an extensive diagnostic study are presented, seeking statistical evidence supportive of spectral multi-scaling. Such evidence emerges from two sources of data. One is a 13 year long historical record of radar observations of rainfall in southeastern UK (Chenies radar), with high spatial (2 km) and temporal (5 min) resolution. The other is an ensemble of rain rate fields simulated by a spatio-temporal random pulse model fitted to the historical data. The results are consistent between historical and simulated rainfall data, indicating frequency-dependent scaling relationships interpreted as evidence of spectral multi-scaling across a range of spatial scales.     

利用地震属性进行砂岩储层横向预测

地震属性分析技术一直是地震特殊处理和地质解释的主要研究内容。随着相关理论的发展,地震属性分析技术已经应用到油气勘探开发的各个阶段。S盆地南部处于勘探开发的前期,具有井少、二维地震测网较稀、储层预测难的特点。由于沉积地层的变化能引起地震波在动力学和运动学上的相应变化,因此利用地震属性能较好地进行储层特征的定性研究,即通过地震多种属性分析,进行研究区内砂岩储层横向预测。其研究技术路线实际上为先找储层,再进行初步油气检测,最后进行勘探目标优选。根据这个技术路线,地震属性的研究则相应地以三个方面的分析为主:即利用振幅属性来寻找砂体富集区,利用有效带宽判断砂层的均质性,再利用频率属性判断其含气性。地震属性分析方法的应用在早期天然气勘探开发具有可以推广的普遍意义。     

岩石节理张开度的分形描述

本文应用分形理论,建立了描述岩石断裂面的自仿射随机分形理论模型。根据该模型探讨了岩石断裂面张开度与自仿射分形维数之间的关系,并对影响张开度的诸因素进行了分析。研究表明,分形维数可用于定量刻划断裂面的平均张开度。     

水泥土结构特性的定量化研究

采用电阻率测试技术,通过测试水泥土在强度增长以及压缩过程中的竖向、水平向电阻,探求水泥土在强度增长过程和压缩过程中电阻率特性参数--平均结构因子F、平均形状因子f以及各向异性系数A变化的基本规律,分析了F, f, A与水泥土物理力学特性之间的关系,证实了这3个参数能对土的结构性进行定量分析。     

兴文石海世界地质公园地质环境敏感度评价

兴文石海是四川省最先入选的世界地质公园,独特的焚、苗文化与“兴文式”喀斯特的完美结合使其成为我国20处世界地质公园中的奇葩。为评价地质公园地质遗迹对外界干扰的抵抗力,将敏感度概念引入地质环境的评价中。在分析石海区域地质环境基础上,选取气候、区域地质条件、地质灾害、土壤背景质量、地质环境破坏速率等7个评价要素和相应的20个评价因子,建立评价指标体系和数学模型;采用权重加权平均法,对公园内地质环境敏感度进行定量评价,提出兴文石海世界地质公园可持续发展的措施。